Disgusting humming sound- please help

mickey disco · Post by **mickey disco** » Sun Apr 08, 2007 5:01 pm

Hi,

I have an intel iMac running Live 6, also using a Focusrute Saffire LE and Event Alp5 monitors. The monitors have attenuation switches on which lets you reduce the volume by up to 20dB, and as I have neighbours I always have the output reduced by the maximum and just have the soundcard output on maximum volume- this is normally enough volume for me. However......

...this afternoon a friend came round to help me mix a track I finished, and as my neighbours were out I adjusted the attenuation switches to get some more volume. A constant humming sound started, which is really, really annoying. After some experimentation, the hum stopped when i unplugged the firewire lead from the soundcard, though the computer was still on. So I think there is possibly a fault on my soundcard and possibly the firewire connection is not shielded???

Does my idea sound feasible? Has anyone else had a similar problem? Is it possible to solve the problem? Or is it a fault on my soundcard? It's only a couple of months old, so if this is the case I should be able to exchange it.

Any suggestions greatfully received!

Tarekith · Post by **Tarekith** » Sun Apr 08, 2007 5:45 pm

Does it happen if you run on battery power, and not with the power supply plugged in?

Lux Libra · Post by **Lux Libra** » Sun Apr 08, 2007 5:57 pm

seems to be a groundloop problem (tarekith's tip will probably prove it)

http://www.ableton.com/forum/viewtopic. ... groundloop

mickey disco · Post by **mickey disco** » Sun Apr 08, 2007 7:08 pm

thanks, will look at some of the tips regarding getting rid of ground loops. Unfortunately it's not a laptop so I can't try it without the power in. And everything is run from one socket, which I'm told is good for minimising ground loops. Just my luck......

JACKAL & HYDE · Post by **JACKAL & HYDE** » Sun Apr 08, 2007 7:11 pm

You could quickly go buy a ground lift plug for a few dollars and see if thats the problem before you go through all the trials.

jesso · Post by **jesso** » Sun Apr 08, 2007 7:42 pm

This happens to me sometimes too with my fireface 400 and G4 or macbook... Always fixes its self when I power everything down and then start it up again...

veggieryan · Post by **veggieryan** » Mon Apr 09, 2007 2:43 am

try the hum-x by ebtech. cleared up my hum even with a poorly shielded electric guitar! I tend to think the ground plug is there for a reason....

mickey disco · Post by **mickey disco** » Mon Apr 09, 2007 12:04 pm

that hum-x looks intersting, but i'm not sure how useful it would be as the soundcard is causing the humming, and that's not plugged into the mains (it's powered by firewire from the mac). do you think it would be useful to plug the mac in to one of the hum-x things?

mickey disco · Post by **mickey disco** » Mon Apr 09, 2007 2:16 pm

stop the press- has anyone got any experience of these? or does anyone think they may solve the problem?

http://www.dolphinmusic.co.uk/page/shop ... t_id/13134

Tarekith · Post by **Tarekith** » Mon Apr 09, 2007 2:31 pm

Are you using XLR plugs? If not, it won't help much. I'd say try th ground lift solution above, if onyl to try and isolate the issue. If the problem goes away using using the ground lift, you know you have a ground loop causing the hum, which is fairly common.

Two options then, use an Ebtech to remove the ground hum, or keep using the ground lift. Technically using ground lifts can be dangerous, but to be honest, I've never heard of anyone having an issue in real use. My laptop is on a ground lift to prevent hum as well when powered.

I find it interesting that the Apple power supplies for computers hve no ground lift when using just the PSU plugs (only two prongs), but they do have ground plug on the adaptor cable that comes with it. I would think that if a ground plug was critical, there would be one on the PSU itself as well.

mickey disco · Post by **mickey disco** » Mon Apr 09, 2007 2:39 pm

Hi Tarekith,

Yes, I'm using XLRs into my monitors so it is feasible (and cheap-ish) to use them. I've spent some time searching the web today and it looks like the Ebtechs may not be available in the UK. I also read that apparently they are designed for 110V use, which I don't think we get in the UK.

As the XLR things are technically ground lifts, would they be safe in use (i.e., no risk of me frying whatsoever) bearing in mind that they would only be in the audio path, rather than the current path?

Sorry for so many questions!

veggieryan · Post by **veggieryan** » Mon Apr 09, 2007 5:04 pm

mickey disco wrote:that hum-x looks intersting, but i'm not sure how useful it would be as the soundcard is causing the humming, and that's not plugged into the mains (it's powered by firewire from the mac). do you think it would be useful to plug the mac in to one of the hum-x things?

yes, you plug the computer into the hum-x.

it works like magic.

let us know when you do so all can see the results.